AR Builders Question - Odd looking Chambering

[wanderingwolf24]

My friend is having issues with his .260 ar10 built with a proof barrel. There seems to be a raised ring right behind the lugs and marring on the lugs where the bolt contacts them (pics attached). The gun will not cycle and all the gas and buffer system has been checked.
I have an ar10 in 308 that I built with Wilson combat barrel and bolt combo that is phenomenal. It has neither of these issues.

Is this a bad chambering by Proof, or is it something proprietary?

Thanks.

 

[turbobrick]

Does the bolt go into battery?

 

[wanderingwolf24]

Does the bolt go into battery?

Bolt goes into battery and will fire a round

 

[RockAndSage]

My friend is having issues with his .260 ar10 built with a proof barrel. There seems to be a raised ring right behind the lugs and marring on the lugs where the bolt contacts them (pics attached). The gun will not cycle and all the gas and buffer system has been checked.
I have an ar10 in 308 that I built with Wilson combat barrel and bolt combo that is phenomenal. It has neither of these issues.

Is this a bad chambering by Proof, or is it something proprietary?

Thanks.

Regarding the marring/peening on the lugs - that barrel extension is clocked a few degrees out of alignment. You can see it in the feed ramps not being centered on their matching surfaces on the upper. That will cause reliability issues in some cases, as the bolt's lugs are impacting with the extension's lugs, instead of sliding past with little/no touching. It can severely slow down the BCG before the round is fully chambered. Contact Proof, initiate a return process.

 

[turbobrick]

Bolt goes into battery and will fire a round

Interesting, maybe there is some pressure on the lugs from that ring and its not allowing the bolt to unlock freely enough. The extension does look off to me. Who installed the barrel? Is the pin slot in the receiver tight and square? The pin undamaged?

 

[wanderingwolf24]

Regarding the marring/peening on the lugs - that barrel extension is clocked a few degrees out of alignment. You can see it in the feed ramps not being centered on their matching surfaces on the upper. That will cause reliability issues in some cases, as the bolt's lugs are impacting with the extension's lugs, instead of sliding past with little/no touching. It can severely slow down the BCG before the round is fully chambered. Contact Proof, initiate a return process.

That’s what I had figured as far as it being overclocked. Proof’s warranty makes it pretty clear they cover nothing that they deem improper installation sadly. Might have to go to Wilson combat or Ballistic Advantage

 

[wanderingwolf24]

Interesting, maybe there is some pressure on the lugs from that ring and it’s not allowing the bolt to unlock freely enough. The extension does look off to me. Who installed the barrel? Is the pin slot in the receiver tight and square? The pin undamaged?

Haven’t been able to get it apart, these are just my preliminary views on it.

No clue who installed the barrel…it was a gifted gun. Whoever he was should’ve done a better job.

 

[RockAndSage]

That’s what I had figured as far as it being overclocked. Proof’s warranty makes it pretty clear they cover nothing that they deem improper installation sadly. Might have to go to Wilson combat or Ballistic Advantage

Try to get hold of a live person over there, and let them know the barrel was built out of spec. That's a factory issue, not an installation issue by the owner.

 

[wanderingwolf24]

Try to get hold of a live person over there, and let them know the barrel was built out of spec. That's a factory issue, not an installation issue by the owner.

I’ll give them a ring and see if they can do anything. Thanks for your comments and hopefully we can get it shooting

 

[RockAndSage]

I’ll give them a ring and see if they can do anything. Thanks for your comments and hopefully we can get it shooting

Good luck. It's not a small issue, especially reliability, and for something that could be expected to be used for longer range or precision shooting, like a .260.

 

[turbobrick]

Try to get hold of a live person over there, and let them know the barrel was built out of spec. That's a factory issue, not an installation issue by the owner.

I don't think one picture is enough to say its not an install issue. People damage the index pin and slot in the receiver all the time, and that will get the extension in the wrong orientation and the gas tube canted which will cause it to rub on the gas key and you'll get all kinds of issues from that. If its not a factory built gun with a warranty, I'd pull that barrel off before I assumed Proof installed a bad extension.

 

[RockAndSage]

I don't think one picture is enough to say its not an install issue. People damage the index pin and slot in the receiver all the time, and that will get the extension in the wrong orientation and the gas tube canted which will cause it to rub on the gas key and you'll get all kinds of issues from that. If its not a factory built gun with a warranty, I'd pull that barrel off before I assumed Proof installed a bad extension.

Good points.